A wide variety of equipment has been developed by which sprays, mowers, etc., may be operated off transport vehicles, such as tractors and other like vehicles, in order to cover extensive areas. Sprays, etc., are commonly mounted off booms in order that tractors travelling along access routes may apply sprays to areas off the access route. Similarly mowers, slashers, etc., working off roadways, utilise booms in order to reach roadside verges and cut down unwanted vegetation. These operations require deployment of boom type structures and fixed booms are of little use. Booms are known which may be swung out of the way. Hydraulically extendible booms similar to those used in crane construction have been used. However, no ready and simple solution has yet been found in the quest for an economical and easily maintained boom, for application off tractors and other like vehicles, to enable operations such as spraying, mowing etc.